Hardly a Karloff vehicle. Boris shot the footage for this and three other Mexican "horror" films in LA, an unfortunate swan song to his career, though he was fortunate to be quickly written out of this story. The near plot concerns a mutant rock that thrives on human fear. Doctor Karloff and his assistants make sure the rock is rolling in sacrificial victims (women, of course). A prodigious devaluation of the "B"-grade horror flick, it's so bad it's just bad.